Suo - Mires and peat vol. 47 no. 1 | 1996
Boreaalisen reunavaikutteisen suokasvillisuuden monimuotoisuuden analyysia.
English title: Patterns of diversity in boreal mire margin vegetation.
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Mire margin communities are mosaics of forest and mire vegetation which consist of several ecological guilds (forest, spruce mire, marsh and spring vegetation). Diversity patterns of undrained forested mire margin communities were examined by using numerical classification (TWINSPAN) and ordination (DCA) techniques. The understorey vegetation was tested for both alfa (species richness, Shannon H' and Pielou J diversity indices) and beta diversity (DCA dimensions). The structural diversity of the overstorey was examined by producing structural (TWINSPAN) clusters based on the percentage cover of tree and shrub species in six canopy layers and in one shrub layer. The study was based on the systematic sample plot data collected from permanent plots of the 8th Finnish National Forest Inventory (1985-86). The material consisted of 92 plots of undrained forested mire margin sites in south and central Finland (60o-66o). The alfa diversities between the seven site clusters differed more clearly than those between the site types. A considerable variety of species of different ecological guilds were found that represented the ecological sources of high beta diversity. Structural diversity varied between clusters formed from overstorey data.
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Korpela,
The Finnish Forest Research Institute, Vantaa Research Center, P.O.Box 18, FIN-01301 Vantaa, Finland
Sähköposti:
ei.tietoa@nn.oo
- Reinikainen, Sähköposti: ei.tietoa@nn.oo
Uuttoajan ja EDTA:n vaikutus metsitettyjen peltomaiden ravinteiden uuttumiseen happamaan ammoniumasetaattiin.
English title: Effect of extraction time and EDTA on acid ammonium extractable nutrient concentrations of afforested agricultural soils.
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The effect of extraction time on the extraction of P, K, Ca, Mg and the effect of EDTA on the extraction of Mn, Fe and Zn with acid ammonium acetate was studied in 196 soil samples collected from afforested agricultural soils. Extraction time (1 hour or ca. 20 hours) did not significantly affect gravimetrically expressed mean concentrations of K, Ca and Mg in mineral soil samples. In peat samples the mean concentration of Ca and Mg with the shorter extraction time was 73% and 81% respectively of the mean concentration obtained with longer extraction time. The mean concentration of P with the extraction time of 1 hour was about 50% of the mean concentration obtained with the longer extraction time in peat and mineral soil samples. Extraction with acid ammonium acetate/EDTA extracted Fe sevenfold and Zn almost threefold compared with acid ammonium acetate alone. Regression models for converting gravimetric and volumetric nutrient values obtained with methods used in agriculture to gravimetric and volumetric nutrient values obtained with methods used in forestry are presented.
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Wall,
The Finnish Forest Research Institute, Kannus Research Station, P.O.Box 44, FIN-69101 Kannus, Finland
Sähköposti:
ei.tietoa@nn.oo
- Urvas, Sähköposti: ei.tietoa@nn.oo
TDR-mittausten kalibrointi viljeltyjen turvemaiden kosteuden mittaamiseen.
English title: Calibration of time domain reflectometry (TDR) for soil moisture measurements in cultivated peat soils.
Avainsanat:
water content;
dielectric number
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Time domain reflectometry (TDR) is a relatively new technique for measuring soil water content. It is based on measuring the apparent dielectric number (Ka) of the soil from the propagation velocity of an electromagnetic pulse travelling in the soil. Soil water content is then calculated from the apparent dielectric number. In this study, an empirical relationship between the apparent dielectric number and the volumetric water content was established for cultivated peat soils in the laboratory. A third-degree polynomial described the relationship with a coefficient of determination of 0.980 and a standard deviation of 0.027 m3m-3. The relationship can be used to measure water content in typical cultivated Sphagnum and Carex peat soils in the range usually prevailing in the field, i.e. 0.3-0.8 m3m-3.
Key words: dielectric number, water content
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Myllys,
Agricultural Research Centre of Finland, Institute of Crop and Soil Science, FIN-31600 Jokioinen, Finland
Sähköposti:
ei.tietoa@nn.oo
- Simojoki, Sähköposti: ei.tietoa@nn.oo
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